<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>梯形</title>
    <style>
        div{
            margin: 10px;
        }
        .isosceles-trapezoid{
            width: 0;
            height: 0;
            padding: 10px;
            border-style: solid;
            border-width: 40px 25px 40px 25px;
            border-color: blue greenyellow green red;
        }
        .isosceles-trapezoid1{
            width: 10px;
            height: 10px;
            border-style: solid;
            border-width: 40px 25px 40px 25px;
            border-color: blue greenyellow green red;
        }

        .isosceles-trapezoid2{
            width: 30px;
            height: 30px;
            background: greenyellow;
            transform: perspective(2em) rotateX(50deg);
            perspective: initial;
            ;
        }
    </style>
</head>
<body>
<!--等腰梯形-->
<div class="isosceles-trapezoid"></div>
<div class="isosceles-trapezoid1"></div>
<div class="isosceles-trapezoid2"></div>
</body>
</html>